Can green tea be used to reverse compromised bond strength after bleaching?

The objective of this study was to evaluate the antioxidant effect of green tea on microtensile bond strength (TBS) to bleached enamel. Forty-two human third molars were randomly divided into six experimental groups (n=7 each group): group 1, no treatment; group 2, bleaching (10% carbamide peroxide); group 3, bleaching+10% sodium ascorbate gel (SA); group 4, bleaching+10% green tea gel (GT); group 5, SA; and group 6, GT. In groups 2, 3, and 4, bleach was applied onto the enamel surface for 6h, every day for 14d. In groups 3 and 5, SA was applied for 1h; and in groups 4 and 6, GT was applied for 1h. Immediately after treatment, the specimens were bonded with Adper Single Bond 2 and Filtek Z350 XT. The TBS of the specimens was tested using a universal testing machine. Fracture mode analysis of the bonded enamel surface was performed using scanning electron microscopy. The mean TBS values for each group were: group 1, 33.2 +/- 5.8MPa; group 2, 22.6 +/- 5.5MPa; group 3, 30.0 +/- 5.2MPa; group 4, 31.6 +/- 3.8MPa; group 5, 29.1 +/- 4.2MPa; and group 6, 32.2 +/- 4.5MPa. All groups had a higher percentage of mixed failures. In conclusion, green tea can be used as an alternative antioxidant on bleached enamel before bonding procedures.121437738